1. Field of the Invention
The present invention relates to a memory module, a memory module socket, and a mainboard using same. More particularly, the invention relates to a memory module providing an increased number of connectors adapted for use as external connection ports to the memory module, a related memory module socket, and a mainboard incorporating same.
2. Description of the Related Art
Contemporary computational systems, such as personal computers (PCs), workstations, notebook computers, and mobile devices such as mobile phones require an increasing variety of functional capabilities. This expanding set of capabilities requires a greater tolerance for different software configurations and hardware add-ons. At the same time, contemporary computational systems are being reduced in physical size while also providing greater data capacities and increased operating speeds.
One result of these commercial motivations is the provision of significantly expanded memory capabilities within contemporary computational systems. The number, speed and complexity of signals (e.g., data, address and control) applied to the various memory resources in such systems have also increased. The number of connection pins (ground, power and signal) connecting this expanding multiplicity of signals is also increasing. This increasing number of memory module pins generally increases the area (and/or number deposition layers) associated with memory modules incorporated within the system. The overall wiring design of the printed circuit boards (PCBs) implementing the various memory modules as well as the incorporating mainboard has been in many instances quite challenging. As a result of this difficulty, further reductions in the physical size of contemporary computational systems has been impeded and the signaling performance associated with constituent memory systems has in some instance deteriorated.
Memory modules are devices mounting a plurality of semiconductor memory devices on a single substrate, such as a PCB. Memory modules commonly group the performance functionality of the memory devices, such as the provision of power/ground signals, control and address signals, etc. Memory modules are commonly connected to one another or to a mainboard using via socket and pin assemblies. That is, a memory module is mechanically inserted into a memory module socket to electrically connect it with the mainboard (sometimes referred to as a motherboard) within a computational system.
Common memory modules include the single in-line memory module (SIMM) type in which contact points are linearly arranged on one side of the module substrate, and the dual in-line memory module (DIMM) type in which the contact points are linearly arranged on both sides of the memory module substrate. Indeed, most memory modules have a structure in which the contact points are arranged along one or more primary sides in a lengthwise direction.
However, when a connector, (such as a Tape Automated Bonded or TAB connector), is formed on a memory module such that its contact points are arranged along only one side, it is difficult to meet the contemporary demands for a greater number of connections. This is particularly true given the decreasing size of many memory modules. Thus, further reductions in the size of memory modules is precluded by a lack of reliable electrical connections.
To begin addressing this problem, another type of memory module has recently been introduced. This memory module includes not only a number of external connection ports formed along the lengthwise direction of module substrate, but also along the widthwise direction (i.e., along the short sides of the memory module).
Figure (FIG.) 1 is a front schematic view of a conventional memory module as it fits into a corresponding memory module socket. Referring to FIG. 1, a total three connectors, including a lengthwise connector 111 and two widthwise connectors 112, are formed on a memory module 110 mounting a plurality of memory devices 115. A memory module socket 120 mounted on a mainboard substrate 150 is adapted to receive memory module 110 and has a U-shaped structure containing socket pins that correspond to connectors 111 and 112.
When edge portions of memory module 110 are inserted into memory module socket 120 from a direction indicated by an arrow in FIG. 1, the pins forming connectors 111 and 112 are electrically connected to the socket pins of memory module socket 120. Thus, memory module 110 is mechanically and electrically connected to mainboard 150 via memory module socket 120. Through this multiplicity of pin connections power, data, control and address signals may be communicated between mainboard 150 and memory module 110.
In the conventional example shown in FIG. 1, the pins forming first connector 111 and second connectors 112 must be mechanically inserted into the socket pins of memory module socket 120. However, this insertion-connection approach presents some structural difficulties. That is, considering the direction at which memory module 110 is inserted into memory module socket 120 and the edge-perpendicular layout of the individual pins forming first connector 111 and second connectors 112, the sheering mechanical force exerted on the pins of second connectors 112 may actually damage the constituent pins.
Ideally, the layout of the pins forming second connectors 120 and/or the socket pins in memory module socket 120 would be re-arranged to avoid this mechanical wear and tear. However, the structure of memory module socket 120 is restricted due to its electrical and physical characteristics and a less wearing mechanical arrangement has not been practically realized. For example, it is difficult to shorten the length of a wiring connection associated with second connectors 112 without the connection to memory module socket 120 becoming electrically unstable.
Many DIMM type memory modules designed for portable use within mobile devices and notebook computers have adopted the so-called small outline dual in-line memory module (SODIMM) layout. The connection approach between SODIMMs and corresponding memory module sockets is different from that of general DIMMs. The SODIMM is inserted in its memory module socket by first being inclined at a predetermined angle with respect to the mainboard substrate and then pivoted toward the mainboard parallel with the surface of the mainboard substrate in order to be coupled within the memory module socket. This increased insertion and layout complexity preclude conventional SODIMMs from having widthwise connectors in addition to lengthwise connectors.
A growing demand exists for a practical connection approach for SODIMMs having expanded connection capabilities.